Czechoslovakian Pat. No. 94,372 teaches a mounting structure with a revolving disc on the main support carrying the mechanism, which disc pivots around a vertical axis. An intermediate body is arranged concentrically below this revolving disc, such intermediate body serving as movable support between the revolving disc and a support plate resting on the ground. Between the intermediate body and the support plate, hinged double acting cylinders, guide bolts and guide bearings are arranged vertically. A separate linear ball bearing race is provided between the revolving disc on the main support and the intermediate body, as well as a double acting cylinder causing the linear feeding. This device has certain disadvantages, however, particularly with respect to construction costs because of the separate arrangement of structural parts which induce and/or effect the required horizontal movement, and the vertical movement. This increases the space requirements for the equipment, as well as material costs. Furthermore, the center of gravity of the mechanism is relatively high, so that the stability of the mechanism is affected.